What principle involves progressively increasing the amount of resistance in strength training?

The principle of Progressive Overload focuses on the need to gradually increase the stress placed on the body during exercise to stimulate muscle growth and strength development. In strength training, this means incrementally raising the amount of resistance — whether by increasing weights, adding repetitions, or changing the intensity of workouts — to ensure that muscles are continually challenged. This ongoing challenge is crucial for adaptation, as the body responds to increased demands by building more muscle fibers and improving overall strength.

In contrast, Specificity of Training refers to the concept that training adaptations are specific to the type of training performed. While important, this principle does not directly address the need for increasing resistance over time. The Function of Muscle Fibers focuses on the characteristics and roles of different muscle types in performance but does not relate to the method of increasing workout intensity. Tendon Elasticity pertains to the flexibility and adaptability of tendons, which can be influenced by training but is not a guiding principle for directly manipulating resistance levels in strength training.

Therefore, Progressive Overload is fundamental for those aiming to improve strength and performance effectively, as it ensures ongoing improvement by systematically challenging the muscles.